TI-83 intervalometer

The headline How to Make Time Lapse Video With Your DSLR didn’t really grab us. Honestly, you pay that much for a camera and it can’t do time lapse out of the box? Well, we nearly missed the real story: [Chris Martino] was using a TI-83 to act as the intervalometer for the camera. The calculator has a 2.5mm audio jack for it’s data port and the camera has an identical port for the shutter trigger. The TI-83 runs a program with a FOR loop to act as the timer. When the loop completes it sends data to the port, and the voltage triggers the shutter. The rate isn’t very exact and varies depending on the charge left in the batteries. [Chris] estimated 10000 program iterations ends up being about 26 seconds between pictures. This technique has been tested on 84, 86, and 89 series calculators too. There are a couple example time lapse videos embedded after the break.

The TI-84 Plus and 84 Plus SE both have a real time clock that you can read using the getTime and getDate functions. You can use a while loop and check this clock using the getTime function (returns a list, hour:minute:second) against a stored list of the previous time. Count the number of seconds using this and you’ll have an accurate timer. This seems like a good use of the data connection, but my camera doesn’t have a port to connect with.

Nice. Time lapsed photography can be interesting when it’s used to capture events that aren’t normally visible. But it’s use in the provided samples is just plain boring, INMO. I have no doubt that, the photographer and subjects get a kick out of viewing the results, though.

What you did provides something you can’t buy on the market. Thank you for sharing! I’m using this technique now as a great cheap alternative for astrophotography. An essential exercise in using a DSLR for astro imaging requires ‘locking up the mirror’ and pausing to eliminate vibration before shutter release, and then also allowing a delay for in-camera processing such as dark frame subtraction. None of the commercial auto timers support this, for $80-$140 bucks all you get a simple exposure timer. Kudos!

To not have to convert the calculator’s iterations into seconds in your head, use this program (below). The multiplier of 300 makes each entered second you put onto the calculator as a second in time for the shutter (approximately… will vary with calc’s battery power). ie… type in 26 to get 26 seconds between each picture instead of 10,000 on the calculator screen to get 26 seconds between each picture.